The invention provides a method for predicting growth efficiency of an animal by using infrared thermography by generating a predictive model, comprising selecting a sample population from a group of animals; scanning each animal to obtain a thermographic image represented as an array of pixels providing temperature data; calculating a value of a statistical measure of the temperature data (input variable); calculating a value of a measure of growth efficiency (output variable); and determining a relationship between the input and output variables to generate a predictive model. The predictive model is then used to predict growth efficiency in an animal from the same group but not in the sample population by scanning the animal to obtain a thermographic image; calculating a value of a statistical measure of the temperature data (input variable); and solving the predictive model to provide the value of the growth efficiency of the animal.